# Electric airplanes

**URL:** <https://boards.straightdope.com/t/electric-airplanes/844530>\
**Category:** Factual Questions\
**Created:** [December 7, 2019, 11:06pm UTC](https://boards.straightdope.com/t/electric-airplanes/844530 "2019-12-07T23:06:38Z")\
**Posts on this page:** 1\
**Showing post:** 111

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**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\
**Post date:** [December 12, 2019, 7:26am UTC](https://boards.straightdope.com/t/electric-airplanes/844530/111 "2019-12-12T07:26:47Z")

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> [@Dr.Strangelove](#):
>
> Not to put too fine a point on it, but you’re directly contradicting NASA here.

No, he’s not. Rather, you’ve misunderstood what’s going on.

> [@NASA](#):
>
> Notably, the majority of the efficiency increase comes from the switch from gasoline piston engines in the baseline aircraft to high-efficiency electric motors, but a substantial increase still occurs due to the improvement in aerodynamic-propulsive efficiency.

Cite: [Comparison of Aero-Propulsive Performance Predictions for Distributed Propulsion Configurations - NASA Technical Reports Server (NTRS)](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170001218.pdf)

So the 3.3x-5x “efficiency” goal involves a much, much smaller drag reduction than you understood. Because piston engines are only about 30% efficient—they waste 70% of their fuel energy as heat—this isn’t an apples-to-apples comparison. (Gas turbines are about 30% more efficient than piston engines in aircraft applications).

In the real world, I’d be thrilled for the X-57 team if the total aircraft drag at 150 KIAS was reduced by 25-50%. A 100% drag reduction would be extraordinary. 15-20% seems realistic to me.

> [@Dr.Strangelove](#):
>
> That’s not to say that you’re definitely wrong–this is still a research program after all–but between you and them, I know who I would put my money on.

Oh, are we betting?!? OK!

Several pilots and at least one aerospace engineer have cautioned you that the 500% number isn’t real—and we’ve explained why. We’ve further fleshed out why the real improvement is likely to be 5-10% of the press-release number. And yet you’re sticking to the press release.

Like the poker aphorism says: if you’ve been at the table half an hour and you don’t know who the sucker is, it’s you.

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